The present disclosure relates to inkjet recording apparatuses, which perform printing by ejecting ink from nozzles.
There are some apparatuses that perform printing with ink. Such an apparatus includes a recording head. The recording head includes a plurality of nozzles. Based on image data, ink is ejected from the recording head onto a sheet. Ink is not ejected from a clogged nozzle. Printing is not performed with respect to such a part of the image data as corresponds to a nozzle that is prevented from ejecting ink. This degrades the quality of the image printed on the sheet. There are cases where nozzle clogging is monitored to prevent such inconvenience. In a known technology, clogging is detected by jetting out electrostatically charged ink from nozzles of a head.
Specifically, there is known a printing-head checking device incorporated in a printing apparatus that is provided with a printing head of which a printing distance from a support surface for supporting a print medium is adjustable, and in which ejection ports are formed through which to eject recording liquid. The printing-head checking device receives the ejected recording liquid, detects an electrical change generated when the recording liquid having been ejected in a charged state is received, detects the printing distance used for the printing, sets the ejected amount of the recording liquid based on the detected printing distance on receiving an instruction to check the printing head, causes the charged recording liquid of the set ejection amount to be ejected while maintaining the printing distance, and makes a judgment on whether or not there is an abnormality in the ejection ports based on the detected electrical change caused by the ejection. The printing-head checking device is designed to perform the checking of the printing head by consuming as small an amount of recording liquid as possible.
A head is provided with a nozzle. For the nozzle, there is provided a piezoelectric element to cause the nozzle to eject ink. When a voltage is applied to the piezoelectric element, a pressure is applied to the nozzle. This pressure causes the nozzle to eject ink.
In printing apparatuses using ink, ink ejection from a nozzle is sometimes prevented. Typically performed to address such a case is, as in the known technology mentioned above, processing of detecting nozzle clogging by ejecting ink. However, it is not just a clogged nozzle that prevents ink ejection. There is a case where the cause that is preventing ink ejection cannot be identified by such clogging detection processing. Then, it can be said that the clogging detection processing has been done in vain. In addition, since the cause remains unknown, there is a possibility that the head will be replaced although there is no abnormality in the head. Heads are generally expensive. Thus, unnecessary replacement of heads should be avoided. There is a challenge in making it possible to identify the cause of an abnormality so that unnecessary clogging detection processing or unnecessary component-replacing operations will not be performed.
It is impossible, with the known technology described above, to check an abnormality without actually ejecting ink. Thus, the challenge mentioned just above cannot be solved with the known technology.